The invention is directed to a gold-containing preparation for coating metallic particles, particularly for coating fired on alloys in the dental art before the facing with ceramic compositions, said preparation consisting of gold powder, an adhesive and a binder of one or more organic solvents and one or more resin components which binder is liquid at room temperature and volatilized or burned at firing temperature.
For many years in the dental art there has been known the facing of crowns and bridges made of fired on alloys with ceramic compositions. Thereby chiefly for esthetic reasons the metallic crown or bridge framework is entirely or partially coated with one or more tooth-colored ceramic layers. Likewise primarily for esthetic reasons gold-rich intermediate layers are used which bestow a warmer colored background to the slightly transparent dental porcelain than is possible to be done by the mostly metallic white customary fired on alloys.
The previously known gold-containing intermediate layer preparations lead to very smooth surfaces and practically cannot be influenced by the dental technician.
The previously known gold preparations are either melted or sintered on and contain gold powder or ball shaped gold particles (German AS No. 2851429), which lead to a uniform layer thickness and a very smooth surface.
On the other hand there has also long been known the significance of a sufficient dovetailing between the metallic fired on alloys and the dental ceramic for a good union. The proportions of the so-called physical union depends directly very strongly on the size, the shape and the roughness of the surface to be joined with the ceramic.
It is known from German OS No. 2525274 to use gold-containing preparations which besides gold powder and a flux also contains porcelain and zirconium oxide powder of very small particle size. However, this preparation leads to an unesthetic gray-white layer in the burning on the fired on alloy.
Therefore it was the problem of the present invention to find gold containing preparations for the coating of metallic portions, particularly for the coatings of fired on alloys in the dental art before the facing with ceramic compositions consisting of gold powder, an adhesive agent and a binder which is liquid at room temperature and is volatilized or burned at firing temperature, which after the firing guarantees the strongest possible dovetailing with the dental ceramic, has an esthetic appearance and makes possible a savings in the use of gold.